[win] Change Chrome Watcher configuration API.

chrome/app/chrome_watcher_command_line_win.h

 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_APP_CHROME_WATCHER_COMMAND_LINE_WIN_H_
 #define CHROME_APP_CHROME_WATCHER_COMMAND_LINE_WIN_H_
 
 #include <windows.h>
+#include <vector>
 
+#include "base/command_line.h"
+#include "base/files/file_path.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/win/scoped_handle.h"
 
-namespace base {
-class CommandLine;
-class FilePath;
-}  // namespace base
+// Class for configuring the Chrome watcher process via the command-line. This
+// accepts configuration from the parent process and generates the required
+// command-line.
+//
+// It provides functionality for the common task of sharing handles from a
+// parent to a child process, automatically duplicating them with the
+// appropriate permissions. These handles are closed when the generator is
+// destroyed so the generator must outlive the process creation.
+class ChromeWatcherCommandLineGenerator {
+ public:
+  explicit ChromeWatcherCommandLineGenerator(const base::FilePath& chrome_exe);
+
+  // Sets a handle to be shared with the child process. This will duplicate the
+  // handle with the inherit flag, with this object retaining ownership of the
+  // duplicated handle. As such, this object must live at least until after the
+  // watcher process has been created. Returns true on success, false on
+  // failure. This can fail if the call to DuplicateHandle fails. Each of these
+  // may only be called once.
+  bool SetOnInitializedEventHandle(HANDLE on_initialized_event_handle);
+  bool SetParentProcessHandle(HANDLE parent_process_handle_);
+
+  // Generates a command-line representing this configuration. Must be run from
+  // the main thread of the parent process. This should only be called after the
+  // generator is fully configured.
+  base::CommandLine GenerateCommandLine();
+
+  // Appends all inherited handles to the provided vector. Does not clear the
+  // vector first.
+  void GetInheritedHandles(std::vector<HANDLE>* inherited_handles) const;
+
+ protected:
+  // Exposed for unittesting.
+
+  // Duplicate the provided |handle|, making it inheritable, and storing it in
+  // the provided |scoped_handle|.
+  bool SetHandle(HANDLE handle, base::win::ScopedHandle* scoped_handle);
+
+  base::FilePath chrome_exe_;
+
+  // Duplicated inheritable handles that are being shared from the parent to the
+  // child.
+  base::win::ScopedHandle on_initialized_event_handle_;
+  base::win::ScopedHandle parent_process_handle_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ChromeWatcherCommandLineGenerator);
+};
+
+// Class for processing a command-line used to start a Chrome Watcher process
+// and exposing the resulting configuration and any shared handles. To be used
+// within the watcher process.
+class ChromeWatcherCommandLine {
+ public:
+  // Causes the process to explode if any inherited handles weren't taken from
+  // this object.
+  ~ChromeWatcherCommandLine();
+
+  // Parses the provided command-line used to launch a Chrome Watcher process.
+  // If this fails any successfully opened handles will be closed prior to
+  // return. Returns a ChromeWatcherCommandLine object on success, nullptr
+  // otherwise.
+  static scoped_ptr<ChromeWatcherCommandLine> InterpretCommandLine(
+      const base::CommandLine& command_line);
+
+  // Accessors for handles. Any handles not taken from this object at the time
+  // of its destruction will cause a terminal error.
+  base::win::ScopedHandle TakeOnInitializedEventHandle();
+  base::win::ScopedHandle TakeParentProcessHandle();
+
+  // Returns the ID of the main thread in the parent process.
+  DWORD main_thread_id() const { return main_thread_id_; }
+
+ private:
+  // Private constructor for use by InterpretCommandLine.
+  ChromeWatcherCommandLine(HANDLE on_initialized_event_handle,
+                           HANDLE parent_process_handle,
+                           DWORD main_thread_id);
+
+  base::win::ScopedHandle on_initialized_event_handle_;
+  base::win::ScopedHandle parent_process_handle_;
+
+  // The ID of the main thread in the parent process.
+  DWORD main_thread_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChromeWatcherCommandLine);
+};
 
 // Generates a CommandLine that will launch |chrome_exe| in Chrome Watcher mode
 // to observe |parent_process|, whose main thread is identified by
 // |main_thread_id|. The watcher process will signal |on_initialized_event| when
 // its initialization is complete.
 base::CommandLine GenerateChromeWatcherCommandLine(
     const base::FilePath& chrome_exe,
     HANDLE parent_process,
     DWORD main_thread_id,
     HANDLE on_initialized_event);
 
 // Interprets the Command Line used to launch a Chrome Watcher process and
 // extracts the parent process and initialization event HANDLEs and the parent
 // process main thread ID. Verifies that the handles are usable in this process
 // before returning them. Returns true if all parameters are successfully parsed
 // and false otherwise. In case of partial failure, any successfully parsed
 // HANDLEs will be closed.
 bool InterpretChromeWatcherCommandLine(
     const base::CommandLine& command_line,
     base::win::ScopedHandle* parent_process,
     DWORD* main_thread_id,
     base::win::ScopedHandle* on_initialized_event);
 
 #endif  // CHROME_APP_CHROME_WATCHER_COMMAND_LINE_WIN_H_